collection of functions within a castor::log namespace to a more object
oriented Singleton pattern.  Pleae note that the code is still far from
finished, I am commit (compiling) code early in an attempt to increase feedback.

levels, e.g LOG_INFO, LOG_EMERG.

C++ exceptions and by having a std::string parameter as opposed to a C string.

Fixed (and simplified) backtrace that went wrong when demangling a function name longer than 200 characters.

when dealing with double copy recalls.

Proper fix by defining a new RECALLJOB_SELECTED2NDCOPY state instead
of hijacking the (deprecated) fileTransactionId.

assignment operator of th Exception class.  Not only your friends
(classes) can play with your private parts (m_message and m_serrno) but
so can you.

    castor::exception::AlreadyInitialized

cancelled

resilient to hardware unavailability.

broken when dealing with double copy recalls.

This fix is not optimal: we're still using fileTransactionId being NULL
as a flag while we should really create an extra status
RECALLJOB_SELECTED2ND or SELECTEDSHADOW. Not on this hot fix...

This commit also includes a simpler way to select new recall candidates,
which makes it more immune to bugs like the above.
Plus a fix related to the precision used to check if a file was
overwritten while being recalled.

Added an std::exception::Backtrace class, providing a backtrace attached to all exception.
Fixed minor side effects (virtual destructors, catch orders) induced by the inheritance from std::exception.

namespace.

cancelled

C++ not be strict enough with the use of const.  I hope this commit fixes these
const problems.  There is still another SLC6 I need to tackle in order to get
TramCity to pass the SLC6 build.

until some work is pulled/rebased from the remote master.  Please also note
that more work still needs to be done before this can be used by somebody else.